Mapping out bare-nosed wombat (Vombatus ursinus) burrows with the use of a drone

Julie M Old,Michael J M Franklin,Simon H Lin

doi:10.1186/s12898-019-0257-5

Abstract

BackgroundWombats are large, nocturnal herbivores that build burrows in a variety of habitats, including grassland communities, and can come into conflict with people. Counting the number of active burrows provides information on the local distribution and abundance of wombats and could prove to be an important management tool to monitor population numbers over time. We compared traditional ground surveys and a new method employing drones, to determine if drones could be used to effectively identify and monitor bare-nosed wombat burrows.ResultsWe surveyed burrows using both methods in eight 5-ha transects in grassland, that was interspersed with patches of tussock grassland. Ground surveys were conducted by systematically walking transects and searching for burrows. Drone surveys involved programming flights over transects to capture multiple images, from which an orthomosaic image of each transect was produced. These were subsequently viewed using ArcMap to detect burrows. A total of 204 individual burrows were recorded by drone and/or ground survey methods. In grassland, the methods were equally effective in terms of the numbers of burrows detected in transects. In the smaller areas of tussock grassland, ground surveys detected significantly more burrows, because burrow openings were obscured in orthomosaic images by overhanging grasses. There was agreement between the methods as to whether burrows were potentially active or inactive for most burrows in both vegetation communities. However, image interpretation tended to classify grassland burrows as potentially active. Overall time taken to conduct surveys was similar for both methods, but ground surveys utilised three observers and more time in the field.ConclusionsDrones provide an effective means to survey bare-nosed wombat burrows that are visible from the air, particularly in areas not accessible to observers and vehicles. Furthermore, drones provide alternative options for monitoring burrows at the landscape level, and for monitoring wombat populations based on observable changes in burrow appearance over time.

Highlights

Wombats are large, nocturnal herbivores that build burrows in a variety of habitats, including grassland communities, and can come into conflict with people
Highresolution spatial imagery captured by unmanned aerial vehicles can facilitate detection and monitoring of invasive plant species in vulnerable habitats, aiding management through identification of new invasions [2]
A total of eight transects were surveyed using both ground and drone survey methods. Both methods detected wombat burrows, the probability of detecting wombat burrows depended on the grassland community in which they occurred, and their likely occupation status

Summary

Introduction

Nocturnal herbivores that build burrows in a variety of habitats, including grassland communities, and can come into conflict with people. Counting the number of active burrows provides information on the local distribution and abundance of wombats and could prove to be an important management tool to monitor population numbers over time. We compared traditional ground surveys and a new method employing drones, to determine if drones could be used to effectively identify and monitor bare-nosed wombat burrows. Counting wombat burrows can be difficult and very time consuming, especially in areas which cannot be accessed by foot or vehicle, and can pose safety and accessibility issues. Highresolution spatial imagery captured by unmanned aerial vehicles (hereafter, drones) can facilitate detection and monitoring of invasive plant species in vulnerable habitats, aiding management through identification of new invasions [2]. Drones have been used to monitor agricultural performance [49], and resolve human–elephant conflicts by removing elephants from corn fields and settlements, reducing risks to elephants and people as well as reducing crop loses [15]

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